Consolidate aura-ingest's OHLC source-open surface onto the engine-native
epoch-ns Timestamp currency: a private seam-owned inverse, a Timestamp-window
opener, a canonical OHLC bundle opener (fixed C4 O/H/L/C order), and a
DataServer/DEFAULT_DATA_PATH re-export + default_data_server convenience — so a
real-data source builds from aura-ingest alone, with the one ms<->ns crossing
owned by the seam. Behaviour-preserving (byte-identical RunReports).
Grounded against the tree via the ground-spec-0052 workflow (25/28 assertions
confirmed; compare.rs compiler-invisible site + AC1 scope fix applied).
refs #80, #81, #92
